First described by Italian anatomist Antonio Valsalva, the sinuses of Valsalva are slight dilations or bulges located in the wall of the aorta opposite three respective leaflets of the aortic valve. Designed to promote closure of the aortic valve upon termination of each cardiac contraction, the sinuses of Valsalva play a critical role in ensuring proper blood flow through the aorta.
Aortic root prostheses used in replacing diseased aortic roots are generally formed from fabric such as the polyester sold under the trademark HEMASHELD. The cylindrical tube is scalloped at one end to match the scalloped shape of each corresponding aortic valve leaflet to which the tube is to be attached. After attaching the scalloped end of the tube to the corresponding leaflets, the other end of the tube is attached to the aorta, thereby replacing the sinuses of Valsalva and a portion of the ascending aorta. Although this cylindrical tube prosthesis is in widespread use, the prosthesis has disadvantages. One significant disadvantage is that although the cylindrical shape of the tube approximates the geometry of the aorta, the shape fails to capture the geometry of the sinuses of Valsalva and of the associated sino-tubular ridge. The functions of the sinuses and sino-tubular ridge are thus sacrificed when the cylindrical tube prosthesis is used as an aortic root graft. Another disadvantage inherent in using the tube prosthesis is that when the aortic valve opens, the leaflets of the valve sometimes hit the wall of the tube graft, which can cause abrasion and ultimately failure of the leaflets. These disadvantages confirm that the sinuses of Valsalva are needed to prevent the leaflets from hitting the tube wall and to promote proper function of the aortic valve.
Since the sinuses of Valsalva play an important role both in closing the aortic valve and in reducing the stress on the leaflets, using the tube graft can compromise the physiological function and longevity of the aortic valve. Surgeons have often realized that using the tube graft is at best a compromise, and that a better graft having a geometry similar to that of the natural aortic root and the sinuses of Valsalva needs to be developed. Prototypes of new grafts have been tested in valve sparing operations, and their valve function studied in vitro in a left heart simulator. The design of the aortic root graft, or prosthesis, considered preferable at the present time has evolved from these experiments. When the aortic valve is attached to this aortic root prosthesis, the physiological function of the valve is the same as that seen in an intact, natural aortic root.
Therefore, it is an object of the invention to provide an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for the biological aortic root segment and an ascending aorta.
It is another object of the invention to provide an aortic root prosthesis which has a geometry similar to that of the natural aortic root.
It is another object of the invention to provide an aortic root prosthesis which preserves the geometry and physiological functions of a biological aortic root when the prosthesis is used in an aortic graft.
It is another object of the invention to provide an aortic root-prosthesis having a geometry that prevents abrasion and failure of the leaflets of the aortic valve by preventing the leaflets from repeatedly hitting the prosthesis wall.
It is another object of the invention to provide an aortic root prosthesis with sinuses having a geometry and design adapted to promote proper blood flow, thereby allowing smooth formation of vortices in a space behind each respective leaflet, which reduces formation of thrombus and emboli.
It is another object of the invention to provide an aortic root prosthesis which includes a leaflet-sinus assembly having a circular cross-section in the circumferential direction of each leaflet, thereby decreasing stress at each leaflet-graft junction.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for a biological aortic root segment of an ascending aorta. The aortic root prosthesis includes a hollow, annular tube having proximal and distal ends and an inner and outer wall, wherein the distal end is attached to the ascending aorta. The prosthesis also includes a plurality of sinuses circumferentially connected to the-proximal end of the tube. Each of the sinuses is adapted for being attached to an aortic wall and includes contouring means for importing a convex contour to an outer wall of the sinus, thereby creating a space between the open leaflet and its respective sinus to prevent impact between the leaflet of the valve and the inner wall of the sinus as the leaflet of the valve opens.
Preferably, the annular tube and the sinuses are comprised of a polyester fabric.
According to one preferred embodiment of the invention, a plurality of Z folds are formed in and extend circumferentially around the tube.
According to another preferred embodiment of the invention, a plurality of Z folds are formed in and extend along the vertical axis of each sinus and parallel to the longitudinal axis of the tube, thereby allowing each sinus to be stretched laterally.
According to yet another preferred embodiment of the invention, the contouring means comprises at least one purse string stitched around each sinus to form two concentric loops. The loops are gathered to form a tear-drop shape, thereby deflecting the convex contour downwardly toward a free end of the sinus remote from the tube.
The purse string preferably comprises 4-0 polypropylene suture.
According to yet another preferred embodiment of the invention, at least one of the loops is stitched approximately two millimeters from the periphery of each sinus.
According to yet another preferred embodiment of the invention, the proximal end of the tube is scalloped around the edge of the proximal end at a depth of at least two millimeters, thereby permitting formation of a sino-tubular junction where each sinus connects with the proximal end of the tube along the edge.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions spaced at equal intercommissural distances.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other, whereby a first intercommissural distance is smaller than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, each sinus is connected to the proximal end of the tube by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances, whereby a first intercommissural distance is larger than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, the valve is a stentless bioprosthetic valve.
According to yet another preferred embodiment of the invention, the valve is a stented bioprosthetic valve.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta in a patient during a valve sparing surgery is provided, which includes providing an aortic root valve prosthesis comprising a cylindrical fabric tube having proximal.and distal ends, wherein the distal end is adapted for attachment to the ascending aorta. A plurality of sinuses are circumferentially connected to the proximal end of the tube. Each sinus is adapted for being attached to an aortic wall. Each of the sinuses is also contoured, thereby imparting a convex contour to an outer wall of the sinus. This contour creates a space between the leaflet in its open position and the respective sinus for preventing impact between the leaflet and the inner wall of the sinus as the leaflet of the valve opens. The method further includes attaching the distal end of the aortic root valve prosthesis to the ascending aorta, and attaching each of the sinuses to a respective leaflet of the aortic valve.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for a biological aortic root segment of an ascending aorta is disclosed, and comprises the steps of measuring the diameter of an aortic valve that is to be spared and forming a cylindrical fabric aortic tube having a proximal end and a distal end, and a diameter equal to that of the aortic valve. The method further includes forming three fabric sinuses for attachment around the periphery of the proximal end of the tube, forming a convex contour on each of the fabric sinuses, and attaching each of the fabric sinuses to the proximal end of the tube.
Preferably, the tube and the sinuses used in the method for assembling an aortic root prosthesis are formed from polyester.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus in equally-spaced relation to the proximal end by respective sino-tubular junctions spaced at equal intercommissural distances.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus to the proximal end by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other, whereby a first intercommissural distance is smaller than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus to the proximal end by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other whereby a first intercommissural distance is larger than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of forming a convex contour on each sinus comprises the steps of stitching at least one purse string around each sinus to form two concentric loops, and gathering the loops to form a tear-drop shaped sinus, wherein the convex contour is deflected downwardly toward a free end of the sinus remote from the tube.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of stitching at least one purse string around each sinus to form two concentric loops further comprises the step of stitching one of the loops at least two millimeters from the periphery of each sinus.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of forming three intercommissural distances on the proximal end of the tube comprises the step of forming three respective scalloped-shaped edges along the proximal end at a depth of approximately two millimeters, thereby permitting formation of a sino-tubular junction where each sinus connects with the proximal end.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of forming the fabric aortic tube comprises fabricating the tube from fabric having a plurality of Z folds in and extending circumferentially around the tube.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis is disclosed, wherein the step of forming the sinuses comprises fabricating the sinuses from fabric having a plurality of Z folds in and extending along the vertical axis of each sinus and parallel to the longitudinal axis of the tube, thereby allowing each sinus to be stretched laterally.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta in a patient during a valve sparing surgery is disclosed, comprising the steps of measuring the diameter of an aortic valve that is to be spared, forming a cylindrical, fabric tube having a proximal end and a distal end, and a diameter equal to that of the aortic valve, and forming three fabric sinuses for attachment to the proximal end of the tube. The method further includes the steps of forming a convex contour on each sinus, attaching each sinus to the tube and an aortic wall so that the convex contour is outwardly-facing, and in such a manner as to create a space between the respective open leaflet in its open position and the sinus to prevent impact between the leaflet and the sinus, and then attaching the distal end of the tube to the ascending aorta.
Preferably, the tube and sinuses used in the method for replacing a biological aortic root segment are formed from polyester.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus in equally-spaced relation to the proximal end by respective sino-tubular junctions spaced at equal intercommissural distances.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus to the proximal end by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other, whereby a first intercommissural distance is smaller than the second and third intercommissural distances.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of attaching each sinus to the tube comprises connecting each sinus to the proximal end by respective sino-tubular junctions. Each of the sino-tubular junctions is spaced at respective intercommissural distances from each other, whereby a first intercommissural distance is larger than second and third intercommissural distances.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of forming a convex contour on each sinus comprises the steps of stitching at least one purse string around each sinus to form two concentric loops, said loops gathered to form a tear-drop-shaped sinus, wherein the convex contour is deflected downwardly toward a free end of the sinus remote from the tube.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of attaching each sinus on the proximal end of the tube comprises the step of forming a scalloped-shaped edge on the proximal end at a depth of approximately two millimeters, thereby permitting formation of a sino-tubular junction where each sinus connects with the proximal end.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of forming the fabric aortic tube comprises fabricating the tube from fabric having a plurality of Z folds in and extending circumferentially around the tube.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta is disclosed, wherein the step of forming the sinuses comprises fabricating the sinuses from fabric having a plurality of Z folds in and extending along the vertical axis of each sinus and parallel to the longitudinal axis of the tube, thereby allowing each sinus to be stretched laterally.
According to yet another preferred embodiment of the invention, a method for assembling an aortic root prosthesis for being implanted into a patient during a valve sparing surgery as a replacement for a biological aortic root segment of an ascending aorta is disclosed, comprising the steps of measuring the diameter of an aortic valve to be spared and forming a cylindrical fabric tube having a diameter equal to that of the valve to be spared. Two lengths are then cut from the tube, thereby creating a first, second and third cylinder, wherein the third cylinder forms a fabric aortic root having a proximal end and a distal end. The method further comprises the steps of cutting the first cylinder open lengthwise, thereby creating a first quadrilateral. Second and third quadrilaterals having equal lengths are cut from the first quadrilateral, thereby creating a first and second sinus from the second and third quadrilaterals. The second cylinder is then cut open lengthwise, thereby creating a fourth quadrilateral. A fifth quadrilateral having a length equal to that of the second and third quadrilaterals is then cut from the fourth quadrilateral, thereby creating a third sinus from the fifth quadrilateral. Next, excess fabric is trimmed from around the edges of each sinus, thereby creating a contour for each sinus by reducing the height and width of each sinus by at least two millimeters. A convex contour is then formed on each sinus by stitching at least one purse string around each sinus to form two concentric loops, and gathering the loops to form each sinus into a tear-drop shape, thereby deflecting a convex contour downwardly toward a free end of each sinus. Three points equal to the widths of the first, second and third sinuses, respectively, are marked around the periphery of the proximal end of the fabric aortic root. The proximal end is then scalloped to form first, second and third scallops thereon in preparation for forming sino-tubular junctions. Scalloping the proximal end in this manner also creates first, second and third respective intercommissural distances. Each of the scallops has a depth of at least two millimeters. Next, a sino-tubular junction is formed by inserting a funnel-shaped object into and through the fabric aortic root, and matching each of the first, second and third intercommissural distances to a respective first, second and third sinus. Finally, each sinus is stitched to form a respective sino-tubular junction by using a running suture beginning in the middle of each scallop, and then catching the purse-string of each sinus in a loop of the running suture, thereby creating the sino-tubular junction.
According to yet another preferred embodiment of the invention, a method for implanting an aortic root prosthesis into a patient during a valve sparing surgery as a replacement for a biological aortic root segment of an ascending aorta is disclosed comprising the steps of providing an aortic root valve prosthesis comprising a cylindrical fabric tube having proximal and distal ends, wherein the distal end is adapted for attachment to the ascending aorta, and a plurality of sinuses circumferentially connected to the proximal end of the tube. Each sinus is adapted for being attached to an aortic wall of an aortic valve which is to be spared. Each sinus also includes contouring means for imparting a convex contour to an outer wall of the respective sinus, thereby creating a space between the leaflet when the leaflet is in an open position and the respective sinus to prevent impact between the leaflet and the inner wall of the sinus as the leaflet valve opens. The method further comprises the steps of scalloping the peripheral edge of an aortic wall, thereby creating a line of leaflet attachment and leaving approximately 2-3 millimeters along the peripheral edge. Orientation sutures are then stitched at respective aortal commissures, and each of the sinuses is then stitched to a respective sino-tubular commissure and along the line of leaflet attachment, thereby attaching each sinus to the respective leaflet and producing suspension of the valve. The distal end is then sutured to the ascending aorta. Finally, first and second holes are formed in the prosthesis for attachment of left and right coronary arteries to the prosthesis. The first hole is formed in a first sinus and the second hole is formed in a second sinus. The left and right coronary arteries are then attached to respective first and second holes.
According to yet another preferred embodiment of the invention, a method for replacing a biological aortic root segment of an ascending aorta in a patient during a valve sparing surgery is disclosed comprising the steps of measuring the diameter of an aortic valve to be spared and forming a cylindrical fabric tube having a diameter equal to that of the valve to be spared. Two lengths are then cut from the tube, thereby creating a first, second and third cylinder, wherein the third cylinder forms a fabric aortic root having a proximal end and a distal end. The first cylinder is then cut open lengthwise, thereby creating a first quadrilateral. Second and third quadrilaterals having equal lengths are cut from the first quadrilateral, thereby creating a first and second sinus from the second and third quadrilaterals. The second cylinder is then cut open lengthwise, thereby creating a fourth quadrilateral. A fifth quadrilateral having a length equal to that of the second and third quadrilaterals is cut from the fourth quadrilateral thereby creating a third sinus from the fifth quadrilateral. Excess fabric is then trimmed from around the edge of each sinus, thereby creating a contour for each sinus by reducing the height and width of each sinus by at least two millimeters. The method further includes the steps of forming a convex contour on each sinus by stitching at least one purse string around each sinus to form two concentric loops and gathering said loops to form each sinus into a tear-drop shape, thereby deflecting a convex contour downwardly toward the end of each sinus. Three points equal to the widths of the first, second and third sinuses, respectively, are then measured and marked around the periphery of the proximal end of the fabric aortic root, and the proximal end is scalloped, thereby forming a first, second and third scallop on the proximal end. Each of the scallops has a depth of at least two millimeters and a corresponding first, second and third intercommissural distance. Three respective sino-tubular junctions are then formed by inserting a funnel-shaped object into and through the fabric aortic root, and matching each of the first, second and third intracommissurial distances to a respective first, second-and third sinus. Each sinus is then stitched along its respective scallop by using a running suture beginning in the middle of each scallop, and by catching the purse-string of each sinus in a loop of the running suture, thereby forming the sino-tubular junctions. Next, the peripheral edge of an aortic wall of an aortic valve that is to be spared is scalloped, thereby creating a line of leaflet attachment and leaving approximately 2-3 millimeters along the line of leaflet attachment for attaching the edge to the sinuses along the line of leaflet attachment. Orientation sutures are then stitched at respective sino-tubular commissures, and each of the sino-tubular commissures is sutured to a respective aortic commissure, thereby producing suspension of the valve. The distal end is then sutured to the ascending aorta. Finally, first and second holes are formed in the prosthesis for attachment of left and right coronary arteries to the prosthesis. The first hole is formed in a first sinus and the second hole is formed in a second sinus, and the left and right coronary arteries are then attached to the respective first and second holes.